h3{
    text-align: center;
}
div{
    text-align: center;
}
ul{
    list-style-type: none;
    text-align: center;
}
li{
    float: left;
}
img{
    width: 150px;
    height: 150px;
    margin-left: 20px;
    margin-right: 20px;
}